Cushioning mechanism



Jan. 3l, 1939. I L. M, CLARK 2,145,585 cUsHIoNING MECHANISM Filed June2, 1937 2 Sheets-Sheet l l l @fm 2, /22 ,.0 0 49 fw Y/ /f U 42 ZL( 3918538 V f M// l l 23 L :4% X' f/ ,f I

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ATTORNEYS Jan. 31, 1939.

L. M. CLARK 2,145,585

CUSHIONING MECHANISM Filed June 2, 1937 2 Sheets-Sheet 2 ATTO'RN EYSPatented Jan. 31,d 1939 PaTE-NT OFFICE aliases I CU SHIONING MECHANISMLeverett M. Clark,` Snyder, N. Y., assignor to Waugh Equipment Company,New York. N. Y.,

a corporation of Application June 2,1937, serial No. 145,963

IICIaimS.

This invention relates to a cushioning mechanism of theenergy-absorbing-type and is concerned more particularly with a vnovelfriction cushioning mechanism which may be employed forvarious purposes,for example, as a draft gear for railway equipment or in connection withbuffers, trucks, etc. The new cushioning mechanism has a wide range ofutility but, since it may be employed to especial advantage as a draftgear, an embodiment of the invention suitable for that purpose will beillustrated and described for purposes of explanation. y y

As is well known, draft gears employed on railway vehicles to protecttheir structure and lading against the shocks to which they aresubjected during switching and when in train service, should have high,energy absorption, low resistance,

smooth action, and sustained initial compression.

The new device is socons'tructed as to have these characteristics and,in'addition, it is rugged and durable and of relatively light weight.

The new cushioning mechanismcomprises acasing, preferably cylindrical inform, which encloses the operating elements of the device and,in oneend, is provided with an internal friction generating surface,preferably of frusto-conical form. Friction shoes,'lying side by side ina circular series, rngage the friction surface and, extending within thcgroup of shoes and projecting outwardly bey `o yond them, is anactuating plunger which has wedging surfaces engaging similar surfaceson the shoes. Movement of the shoes into the casing is resisted byspring means and, to insure that the shoes will take part equally in thecushioning action, the shoes are sub-divided into two groups with themembers of the groups lying in alternation. Spacer and equalizerelements are mounted within the casing to engage ,the shoes and thespacer element has parts engaging all .of the shoes and holding themproperly spaced circumferentially of the friction generating surface,andother parts by which forces lengthwise of the casing are transmittedto the shoes of one group. Ther equalizer engages the shoes of the othergroup for transmitting thereto forces applied lengthwise ofthe casingand the spring means takes the form ofa pair of coil springscon'centrically arranged, one spring acting on the spacer element andthe other on the equalizer o element. The springs are undersubstantially the same initial loading and have substantially the samecharacteristics so that theyl operate with ,the same effect to resistinward movement of the shoes of the two groups. For a betteryunderstanding of the l' invention,

referenceA may be made to the accompanying drawings in which:

Figure 1 is a view in longitudinal section of the rangement of the shoesand the spacer and equalizer elements;

Figure 7 is an elevational View of the innerV surface of the shoe;

Figures 8 and 9 are opposite end views of the shoe;

Figures i0. and 11 are pian and elevational views, respectively, of theequalizer element; and

Figures 12 and 13 are plan and; elevational views, respectively, of thespacer element.

Referring to the drawings, thev device is illustrated at Figure i asincluding a casing 2t which is preferably of cylindrical formation,since a casing of that shape permits expansive stresses to be readilyequalized. At one end, the casing is closed and at this end is a iiange2i of generally rectangular shape. In the installation shown in Figurei, the casing lies between the usual longitudinai sills i2 fof a railwayvehicle and the iiange 2i engages draft stops 23 secured to the sills inthe usual manner. A

The opposite end of the casing is open and adjacent this open end, thecasing is formed with an internal friction generating surface 2t whichmay be and preferably is a frusta-conical formation. The surface is ofsumciently large area to obtain the necessary cushioning capacitywithout undue abrasion and the inward taper of the surface provides theproper rate of capacity increase of the device in operation. Within thecasing at the open end, are friction shoes 25, each of these shoes beingarcuate in section with the outer curved surface in contact with thesurface` 24 .of the casing. The curvature of the friction surfaces ofthe shoes is so related to that of the surface 24 that the maximumcontact is obtained when the shoes are at the limit of' their inwardmovement. into the casing. Each formed on its rear surface with atransverse lug 26, one lateralf surface 2l of which is iiat while theopposite lateral surface 2t is inclined. Extending from the surface 211,lengthwise of the shoe is a rib 29 and the end of the shoe may have arecess 30 in alignment Withtherib.

shoe is An actuating plunger 3| having a circumferential inclinedwedging surface 32, is mounted to extend withinthe series of shoes withthe wedging surface 32 contacting with the surface 28 on the shoes.The-plunger has a stem 33 with a bore therethrough anda bolt 34 passesthrough the bore and has a nut 35 which lies in a recess.

36 in the outer end of the plunger. The bolt projects through the closedend of the casing and. at that end has a head 31 lying within a recess38 in the casing end. The bolt limits the outward movement of theplunger relative to the casing.

Within the group of shoes is a spacing element 39, having the formI of aring and provided with radial recesses 4l in its outer surface, vtherecesses being equally spaced so that each one may receive the rib 29 ofa shoe. On opposite sides of alternate recesses are outwardly extendinglugs 4I which bear against the at lateral surfaces 21 of lugs 26 ofalternate shoes. When the spacer is in position, the interengagement ofthe ribs of all the shoes in thenotches 40 causes the spacer to hold theshoes in properly spaced circumferential relation and the lugs 4I on thespacer engaging the abutment surfaces 21 of lugs 26 of the shoes of onegroup permit forces length- Wise of the casing to be transmlttedthroughthe spacer to the shoes of one group only.

At the inner end of the series of shoes is an equalizer element 42through which forces lengthwise of the casing are transmitted to theshoes which are not engaged by the lugs 4I of the spacer. The equalizer,accordingly, contacts with the shoes of the second group only and forthis purpose mayl lhave theform of a ring provided on one face with aplurality of projections 43, each of which has a pair of fiat endsurfaces 44 separated by a rib 45. The equalizer is mounted in positionwith the ribs 45 entering the notches 30 in the shoes of the secondgroup and the end portions on either side of the notch at the end ofeach such shoe bear against a pair of surfaces 44 on the equalizer. Theribs 45 are of smaller dimensions than the notches in which they arereceived so that the equalizer takes no part in maintaining the shoes ofthe series in proper circumferential relation.

Mounted within the casing are inner and outer coil springs designated46, 41, respectively, these springs bearing against the closed end ofthe casing and against the spacer and equalizer elements, respectively,and the end convolutions of each spring are preferably flattened, asindicated at 48, so that the springs may havea good bearing against theinner .end wall of the casing and against the flat faces of the spacerand equalizer. The springs are installed under substantially the sameinitial loading and they are of similar resistance characteristics sothat inward movement of all the shoes will be equally resisted by thetwo springs.

Outside the casing and in engagement with the outer end of the actuatingplunger is a follower block 49 which engages draft stops 50 secured tothe sills 22 in the usual manner. A yoke 5| encircles the cushioningmechanism and follower block, and the yoke at its forward end receivesthe shank 52 of a coupler, the rear end ofwhich bears against theorrterface of the follower block.

In the operation ofthe device as illustrated, its overall length isshortened by the plunger being forced into the casing, carrying the'shoes with it and thereby generating friction. In draft, the casing ismoved .relative to the. shoes and plunger by the rear end of yoke 5lwhich is drawn forward sive stresses.

- by the coupler, while in buff, the shoes and plunger are forced intothe casing by the coupler shank acting against the follower 49. Theinward movement of the plunger and shoes relative to the casing takesplace against the resistance of the springs, and the force of thesprings acting through the wedging surfaces on the shoes and plungertends to force the shoes radially outward. Friction is developed betweenthe shoes and the conical surface in the casing in part by the action ofthe springs tending to force the shoes outwardly, and in part by thedecreasing ydiameter of the surface.

In the normal or released position of the mechanism, the springs exert apressure of the order of 6000 to 7000 pounds, and this pressure actingthrough the engaging surfaces of the shoes and plunger forces the shoesradially outward against the conical surface in the casing, and offersresistance to inward movement of the shoes, constituting what is knownas theinitial compression of the mechanism. Whenever a force of sumcientmagnitude is applied to the cushioning device to overcome the initialcompression, the plunger and shoes are moved into the casing; with theresult that the casing is subjected to expan- During the. inwardmovement of the shoes, the radial pressure tends to increase until thereaction of the casing under expansion, operating through the coactingsurfaces on the shoes and plunger, overcomes the adhesion of thesurfaces to each other and produces a movement of the shoes inwardlywith respect to the plunger. 'I'his results in thereduction in theeffective out- .side diameter of the group of shoes and correspondinglyreduces the pressure of the shoes against the casing. In certain priordevices of this sort, the static adhesion of the parts is so great thatthe inward movement of the friction generating elements relative to theplunger or actuat-` vehicle structure. In the device of the invention,-

the subdivision of the six shoes into groups of three insures equalinitial pressures of all of the shoes against the friction surface ofthe casing,

on the shoes and plunger is of relatively low value and the slipping ofthe shoes relative to the plunger may occur several times during thecompression of the device. When the compressive force is removed, theexpansive force of the casing acts through the shoes to causethe/plunger to be expelled slightly with respect to the shoes. Thepressure of the shoes against the casing is thereupon reduced to thatarising from the action of the coil springs, and since the frictionalengagement of the shoes and casing can be over come by that component ofthe spring force which is directed outwardly, the springs act at once.to restore the operating parts `to their normal or released position.

The springs employed have a relatively high capacity in the normalcondition of the device y and because of the balanced pressuredistribution, the static adhesion between the engaging surfaces andtheir capacity does not greatly increase dursprings employed in similarcushioning devices of former constructions.

The device is generally similar in operation to that disclosed in myprior Patent No. 2,052,166, August 25,1936, but differs therefrom inthat the shoes are sub-divided in to two groups with the inward movementof the shoes of each group resisted in part by a separate spring. In thedevice of the patent, it has been found that as a result of variationsin the formation of the shoes, certain shoes may not bear rmly againstthe friction surface, so that these shoes take less part in thegeneration of friction than the others. Preferably, six shoes areemployed in the patented device and it is difficult, within the limitsof cost permitted, to construct that device in such manner that all sixshoes will function equally. In the present device, six shoes areemployed but, because of the sub-division of the shoes intotwo groups ofthree, a three point bearing of each group of shoes on the frictionsurface'is thereby obtained. Thismakes it possible to insure that all ofthe shoes `ilill take part equally -in the generation of friction.

In the new device, the springs are wound in the same direction and asthe springs are compressed, the ends have a rotary movement in onedirection and the reverse movement occurs when the springs expand.,During the compression of the device with the shoes moving inward, theengagement of the shoes with the friction surface of the casing preventsthe rotary action of the ends of the springs from having any effect, buttorsional energy is stored in the springs. When the external "pressureis removed, the initial reaction of the shoes momentarily lessensl theirengagement with thefsurface of the casing to such an extent that thestored torsional". energy in the springs produces a slight movementmfthe spacer and equalizing elements, the former acting to rotate theshoes within the casing. As a result, the shoes shift circumferentiallywith respect to the friction surface during a series of operations, andthe possibility of the shoes wearing grooves lengthwise of the surfaceis avoided. In those devices in which' such groove wear takes place, theexpansive stresses ultimately become unbalanced and the casing may failprematurely in service. Also, in those devices in which the frictionsurface becomes grooved, a. blow of unusually highl magnitude willoccasionally cause the shoes to become'displaced circumferentially, withthe result that the shoes may contact with only relatively small ridges.During subsequent closure of the mechanism, suiicient heat may bedeveloped on these small areas of contact to cause the shoes and casing'to become partially welded together with the resultV that the mechanismfails to release. In the present device,- these objectionable results ofwear on the casing are presented.

Ihe new device affords the several advantages made available by thedevice of the patent, and, in addition, is so constructed to insure-thatall shoes will take part equally in the operation. This insuresthat devices of the new construction willv all have similar operatingcharacteristics.

I claim: ,l l. A cushioning mechanism which comprissva casing, acircular series of friction shoes in the -casing with the shoes arrangedin two groups, the

members of the groups alternating in the series, a central actuatingplunger extending within the series of shoes, the plunger and shoeshaving cooperating wedging surfaces, a spacer having parts engaging allthe shoes to hold them circumferentially spaced and other parts engaging-the shoes -of one group only, an equalizer engaging the shoes of thesecond group only, and a pair of springs within the casing and acting onthe shoes, one spring resisting the inward movement of the shoes of thefirst group and the other resisting lengaging the shoes of the secondgroup only, and

a pair of springs within the casing, one spring engaging the spacer andthe other the equalizer, said springs, respectively, resisting inwardmove-- ment of the shoes of the two groups.

3. A cushioning mechanism which comprises a casing, a circular series offriction shoes in the casing with the shoes arranged in two groups, themembers of the groups alternating in the series,

a central actuating plunger extending within the series of shoes, theplunger and shoes having cooperating wedging surfaces, a spacer havingparts engaging all the shoes to hold them circumfer-` entially spacedand other parts engaging the shoes of one group only, an equalizerengaging the shoes of the second group only, and a pair of coil springswithin the casing engaging, respectively, the spacer and 4equalizer andresisting inward move.` ment of the shoes, said springs being wound inthe same direction.

4. A cushioning mechanism which comprises a casing, a circular` seriesof friction shoes in the casing in engagement with a wall of the casing,

the shoes being arranged in two groups with theV members of the groupsalternating, a central actuating plunger extending within the series ofshoes, the plunger and shoes having cooperating wedging surfaces, meansconnecting the plunger and casing and limiting the movementvof theplunger outward from the casing, spacer and equalizer elements in thecasing,`one of said elements engaging all the shoes to retain them inproper circumferential spacing and having parts engaging the shoes ofone group to transmit thereto forces acting lengthwise of the casing,the other element engaging the shoes of the second group to transmitthereto forces acting lengthwise of the casing, and a pair of springswithin the casing acting, respectivelyfthrough the individual elementsto resist inward movement of the shoes.

5. AIn a cushioning mechanism', the combina'-J tion of a circularseriesof friction shoes, each shoe having an outer arcuate friction surface, apairl of spaced operating surfaces,l and a wedging 'surface, a spacerelement having parts interengaged with'all the shoes of the series tohold the shoes in proper circumferential relationA and having operatingsurfaces vengaged with one operating surface of each of the alternateshoes in the series, an equalizer element having surfaces engaging the'other operating surfaces of all the remaining shoes, and a pair ofsprings engaging the spacer and equalizer elements, respectively.

6. In a cushioning mechanism, the combination of a casing, a circularseries of vfriction shoes inf imy the casing with the shoes arranged intwo groups,

the members of the groups alternating in the series, a central actuatingplunger extending within the series of shoes, the plunger and shoeshaving cooperating wedging surfaces, separate spring means between oneend of the casing and the respective groups of shoes, a member inter;

- posed between one spring means and surfaces on the shoes of one grouponly for receiving and transmitting the force of that spring to theshoes of that group only, the other spring means acting on differentparts of the shoes of the other group .only, and means for limiting themovement of the end of the casing and the shoes, one spring acting onthe inner ends of the shoes of one group only to resist inward movementof said shoes, a mem- .ber interposed between the other spring anddifferent parts of the shoes of the second group only, said other springresisting the inward movement of the shoes of the second group only, andmeans limiting the movement of the plunger out of the casing. J1

8. In a cushioning mechanism, the combination of a casing, a circularseries of friction shoes in the casing with the shoes arranged in twogroups, the members of the groups alternating in the series, a centralactuating 4plunger extending within the series of shoes, the plunger andshoes having cooperating wedging surfaces, a pair of coil springs lyingone within the other between one end of the casing and the shoes, amember interposed `between the shoes of one group and the adjacent endof the inner spring for receiving and transmitting the force of thatspring to surfaces of the shoes of said gro'up'only, the outer springacting on other surfaces of the shoes of the other group only, and meanslimiting the movement of the plunger out of the casing.

9. In a cushioning mechanism, the combination of a casing having afriction generating surface,

*a closed series of six friction shoes inthe casing having surfaces inengagement with the friction generating surface of the casing, the shoesforming two groups of three shoes each with the members of the groups inalternation, a central actuating plunger extending within the series ofshoes,

- wardly from the casing.

second spring engaging said end of the casing and acting through endsurfaces of the shoes of the second group only to resist inward movementof the shoes of said group, and means for limiting the outward movementof the plunger relative to the casing.

10. In a cushioning mechanism, the combination of a casing'having afriction generating surface, a closed series of six friction shoes inthe casing having surfaces in engagement with the friction generatingsurface of the casing, the shoes forming two groups of three shoes eachw-iti the members of the groups in alternation, a central actuatingplunger extending within the series of shoes, the plunger and shoeshaving` cooperating wedging surfaces, a spring engaging one end of thecasing and exerting a force against surfaces of the shoes of onegrouponly to resist movement of the shoes of said group into the casing, saidsurfaces being disposed between the ends of said shoes, a second springengaging said end of the casing and exerting a force against endsurfaces of the shoes of the other group only to resist inward movementof'the shoes of said group, and means for limiting the outward movementof the plunger relative to the casing.

11. In a cushioning mechanism, the combination of a casing having afriction generating surface, a closed series of six friction shoes inthe casing having surfaces in engagement with the friction generatingsurface of the casing, the shoes forming two groups of three shoes eachwith the ymembers of th groups in alternation, a central actuatingplunger extending within the series of shoes, the plunger and shoeshaving cooperating wedging surfaces, a spring engaging one end of lsaidshoes different from the locations of said surfaces on the shoes of theother group, and means for limiting the movement of the plungerout-LEVERETI M. CLARK.

